The present invention relates generally to plastic containers having an inner pouch fixed within an outer chamber and, more particularly, to such containers and to methods for making such containers that are especially, although not exclusively, useful in liquid storage or processing applications such as the processing, storing and treating of biological fluids such as blood and blood components
In the medical field, plastic containers having outer and inner pouches and/or compartments are known. For example, International Publication No. WO 96/40857 discloses containers useful for removing certain compounds in blood products that have been treated to inactivate pathogens in the blood products. The containers disclosed therein include an outer plastic container and an inner free floating pouch typically made of a liquid permeable mesh.
The mesh pouches may contain an adsorbent material capable of removing certain compounds used in the pathogen inactivation process. The outer chamber receives the blood product that has been subjected to the pathogen inactivation process. The liquid permeable mesh allows the blood product to contact the adsorbent, while retaining the adsorbent with the pouch.
The pouches are typically made of two sheets of mesh material sealed together along their peripheral edges or a single sheet of a folded mesh material sealed along a portion of its peripheral edge. The reliability of the seal along the peripheral edges of the pouch is important to ensure that adsorbent material does not enter the chamber where the blood product is retained.
U.S. Pat. No. 4,976,707 discloses a fluid storage apparatus which includes an inner flexible container enclosed within an outer flexible container. The interior container may hold a liquid, and the outer container may be filled with gas or air to exert pressure on the interior container and thereby expel the liquid from the interior container. In one embodiment, the peripheral edges of the interior container and exterior container are sealed together, forming an integral multi-compartment container.
U.S. Pat. No. 4,235,233 discloses a blood bag having an upper fluid storage portion and a lower filter portion that includes a filter media. The storage portion is separated from the filter portion by a temporarily sealed outlet. The seal may be broken to allow blood to flow from the upper storage portion into the lower filter portion and, more specifically, through the filter media. As shown in FIGS. 5 and 6 of the ""233 patent, at least the two side edges of the filter portion are sealed between the side edges of the blood bag, the bottom edge of the filter media is either the fold of the filter media or a seal, and the top edge contains an inlet tube for liquid flow through filter.
Although the above described containers may have worked satisfactorily for their intended purposes, further improvements in reliability and in the ease of manufacturing such containers are desirable.
The present invention, in one aspect, is embodied in a container having a first wall and a second wall joined to define an outer liquid receiving chamber having a peripheral edge. The peripheral edge is defined, at least in part, by a seal between the first and second walls. The container includes a pouch fixed within the liquid receiving chamber. The pouch includes first and second facing walls joined to define an inner chamber. In one aspect of the present invention, at least a portion of the first and second inner pouch walls are liquid permeable. The inner chamber is closed to the exterior except through the liquid permeable portion. The pouch walls are located between the first and second outer chamber walls and are sealed with the first and second walls along a portion of the seal.
In another aspect of the present invention, the inner pouch is made of a folded sheet of a polymeric material. The polymeric material may be made of a biocompatible material such as polyester. The container may be made of a thermoplastic material including, but not limited to, a blend of polymers and/or copolymers. In another aspect of the present invention, the melting point of the thermoplastic material is lower than the melting point temperature of the polymeric material of the inner pouch.
In one aspect of the present invention, the container includes first and second walls of a thermoplastic material joined to define a liquid receiving chamber having opposed side edges and opposed end edges defined by lines of seal between the first and second walls. The container includes a pouch fixed within the liquid receiving chamber. The pouch is made from a single sheet of a polymeric material folded along a fold line to form facing panels having opposed end edges and opposed side edges. One of the end edges is defined by the fold line and the other end edge and side edges are sealed, respectively by the line of seal defining one of the end edges and the side edges of the liquid receiving container to define a closed interior chamber within the pouch.
The present invention is also directed to a method for making a plastic container. The method includes providing two sheets of a thermoplastic material. The method further includes forming a pouch including two facing walls defining a pouch chamber, a closed edge and an oppositely disposed open edge. At least a portion of the pouch walls are liquid permeable. The pouch walls are located between the two thermoplastic sheets. A seal is formed between the sheets and the pouch walls are captured at the open pouch edge within the seal, whereby the pouch chamber is closed to the exterior except for the liquid permeable portion.
In another aspect of the present invention, the inner pouch is formed by folding a sheet of a porous polymeric material. The pouch includes a chamber defined by two facing walls and includes a closed edge and one or more open edges. The crease of the fold provides the closed edge while the one or more remaining edges of the pouch are open. The pouch is placed between the first and second sheets of thermoplastic material so that the one or more open edges of the pouch are substantially co-incident with the peripheral edges of the thermoplastic sheets that will define a liquid holding chamber. The thermoplastic sheets are sealed together substantially at the peripheral edges to provide an outer liquid holding chamber and to seal the remaining one or more open edges of the inner pouch.